Driven by the technology and imperativeness of the human genome initiative, emphasis in comparative gene mapping in model species has increased in recent years. In addition to coordination of comparative gene analysis across mammals, our laboratory has extended a strong initiative to provide a comprehensive gene map for the domestic cat (Felis catus). The map consists of two locus categories: Type I, evolutionary conserved coding gene loci of use for comparative reference and Type II loci, hypervariable micro- and minisatellite loci with high polymorphism content and of high value for pedigree analysis of disease phenotypes. We have designated a list of 321 anchored reference Type I loci for comparative inference and are placing these on a cat linkage map using interspecies backcrosses between F. catus and Prionailurus bengalensis, the Asian leopard cat. To date, over 80 interspecies hybrid offspring have been born following artificial insemination; of these, 12 healthy females are maturing and 37 backcross offspring have been obtained. Over 300 microsatellite classes have been selected from an M13 phage library. The loci were sequenced and polymerase chain reaction primers designed and synthesized for polymorphism screens. Methods for in situ hybridization of feline metaphase chromosomes using biotin- labeled molecular clones have been attempted and improved. Procedures using human chromosome libraries for chromosome "painting," i.e., visualization of homologous chromosome segments between carnivores and primates, are in progress. A preliminary physical map of Ateles (spider monkey) has also been constructed using somatic cell hybrids and aligned with the human and other primate gene maps.